Environmental Engineering Reference
In-Depth Information
that represent the large majority of guideline values in
Table 8.7
are above
exposure concentrations that have been linked to HCHO-related symptoms
in epidemiological studies.
Used properly, guidelines can serve as useful tools for investigators to
evaluate the probability that building-related health complaints are related
to contaminants measured. As such, they should not be used as “magic
numbers” that divide safe and unsafe levels of exposure. They are reference
values from which judgments can be made relative to the potential role of
specific contaminants in the observed problem and what mitigation mea-
sures should be implemented. These judgments should include a consider-
ation of consensus-based guidelines and recent scientific literature. The
investigator should also use good sense, particularly when the facts of the
exposure strongly indicate that the contaminant in question is the cause of
the complaints.
The use of guideline values poses other concerns. These include the
unavailability of guidelines for some contaminant exposures, limitations of
environmental testing based on one-time sampling, and conduct of contam-
inant measurement simply because guidelines exist. In the absence of guide-
lines, attempts to relate symptoms to exposures should be consistent with
toxicological and epidemiological evidence. For example, it makes good
scientific sense to consider solvent exposures when symptoms/health com-
plaints are of a neurotoxic nature.
Exposures to gas and particulate-phase contaminants vary significantly
over time. As indicated previously, there is a risk that the results of one-time
sampling may be misinterpreted (when compared to guideline values) if little
or no consideration is given to the potential range of contaminant levels that
may occur or have occurred. Results are more likely to be misinterpreted
when one-time sampling results are in the low end of their range of variation.
Based on information gathered
from building managers and occupants, the on-site investigation, and envi-
ronmental measurements, the investigator should be able to formulate one
or more hypotheses that might identify the cause or causes of complaints
which can be tested by implementation of mitigation measures. Such testing
should involve a quantitative assessment of symptom/complaint prevalence
and targeted environmental measurements. These results should be com-
pared to those obtained in the original investigation. Though such a follow-
up assessment is technically desirable, building owners/managers do not
commonly request them after investigators report results of their initial
assessment of the cause(s) of complaints and their control recommendations.
b.
Hypothesis formulation/testing.
4. Political considerations
Most problem building investigations have both technical and political
dimensions. Many investigators have a technical background and therefore,
by their education, training, and experience, are relatively well suited to
conduct problem building investigations. On the other hand, most investi-
